1. Field of the Invention
The present invention relates to an improved structure for a scraper to be used with the screw mechanism, in particular, a hooked dust scraper for ball screw unit to effectively prevent possible foreign materials such as dust, culls and adulterates from infringing into the spiral passage of the ball screw unit by removing them in advance ahead of the moving screw nut so as to protect the balls screw unit from excessive abrasion.
2. Description of the Prior Art
A screw mechanism has been applied in the mechanical engineering field for a long time. Basically the rotating motion of a screw bolt is converted to the linear motion of a nut so as to transmit a working piece. Among the existing screw mechanism the ball screw unit is the best efficient one because the traveling of the nut on the screw bolt is carried out by a plurality of balls rolling along the spiral grooves formed therebetween.
However, if the above mentioned foreign materials are stuck on the screw bolt, they might enter the passage of the rolling balls so as to retard the movement of the bolt or even seriously damage the ball screw unit by excessively abrasing the spiral grooves formed between the screw bolt and nut serving as a rolling passage for the balls. Therefore, installation of a scraper to remove the dust to clean the rolling passage is absolutely necessary.
A perspective view of conventional a scraper for a ball screw unit is shown in FIG. 10 in which a screw bolt 1 is couple with a nut 23. In this structure a scraper 60 is provided for equipping between the contact surface of the screw bolt 1 and the nut 23 at both ends of the nut 23. The scraper 60 is fixed to the nut 23 with a fixing screw 70 screwed into screw hole 231. The construction of the scraper 60 formed as such has to undergo a tedious and time consuming machining process by at first drill a screw hole 231 on the nut 23, then rotating the scraper 60 into the nut 23 on the bolt 1, then drill a hole on the scraper 60 at the positions corresponding to the screw hole 231 for screw combing the scraper 60 with the nut 23 by a fixing screw 70. During such tedious machining process, it is probability to happen the defective operations, for example, forgetting to apply one or two screws, piercing accidentally the screw bolt when drilling the screw hole, and unstable installation of the scraper due to its insufficient thickness, etc.
For these defects noticeable on the prior art, an improvement is seriously required.
The inventor has dedicated great efforts for years to studying and improving these defects and come up with a novel hooked dust scraper for ball screw unit as provided in this invention to eliminate the defects mentioned above.